This invention relates to an elastically stretchable composite sheet and more particularly to such a composite sheet comprising an elastic sheet and a sheet-like fibrous assembly.
It is well known to bond elastically stretchable nonwoven fabrics to an elastically stretchable sheets made of plastic elastomer or the like and thereby to convert a rubber-like touch intrinsic to the elastically stretchable sheet to a cloth-like touch. For example, in order to provide a liquid-impervious backsheet of a disposable diaper with an elastic stretchability, it is also well known to laminate an elastically stretchable nonwoven fabric on a liquid-impervious and elastically stretchable sheet.
In the composite sheet obtained by such a lamination, staple fibers each having a fiber length of about 50 mm have usually been used. Such composite sheet has had a problem that the staple fibers entangled together and forming the nonwoven fabric would be progressively disentangled one from another as the composite sheet is stretched. As a result, a proper structure of the nonwoven fabric as well as a proper structure of the composite sheet would be impaired and/or become fluffy unless entanglement spots of fibers and/or bond regions between the nonwoven fabric and the elastically stretchable sheet are distributed as densely as possible. However, the spots and/or the bond regions densely distributed will make it difficult to obtain a composite sheet having a high elastically stretchability.
An object of the invention is to eliminate or minimize factors impairing a stretchability of an elastically stretchable composite sheet and thereby to achieve its stretchability as high as possible.
According to this invention, there is provided an elastically stretchable composite sheet comprising an elastic sheet having a stretchability in two directions orthogonal to each other and a sheet-like fibrous assembly having an extensibility in the two direction bonded to at least one surface of the elastic sheet, wherein: the fibrous assembly has a inelastic extensibility, the elastic sheet and the fibrous assembly are bonded together at bond regions arranged intermittently in the two directions and component fibers constituting the fibrous assembly are long fibers continuously extending and describing curves between each pair of adjacent bond regions in which the long fibers are bonded to the elastic sheet.
The elastically stretchable composite sheet according to this invention enables the elastic sheet and the fibrous assembly to be reliably held in their condition bonded with each other even if the bond regions in which these elastic sheet and fibrous assembly are bonded with each other. This is for the reason that the extensible fibrous assembly laminated at least one surface of the elastic sheet comprises the continuous fibers. With the composite sheet obtained in this manner, its stretchability is not affected by the bond regions arranged at close intervals as they have conventionally been the case. The composite sheet of this invention is stretchable but offers a cloth-like comfortable touch by the presence of the continuous fibers. Therefore, this composite sheet is suitable as the stock material for garments such as disposable diapers, sanitary napkins or disposable gowns.